Four-Speed A-Body Clutch Pedal Adjustment - A Clutching Result - Tech

Many drivers of four-speed A-Body cars have complained over the years that they have difficulty shifting gears during a hard-acceleration situation. I'm here to tell you that the main source of the problem may not be the driver. Most likely, it's the clutch pedal. When four-speed A-Bodies first hit the dealers, the clutch pedal ratio was better than that of later A-Bodies. The reason for this is that Chrysler eventually shortened the ratio of the pedal so that the little lady with the six-cylinder car would have a softer, easier pedal to push down. Our '68 Hemi four-speed cars had a very good ratio on the pedal and did not have this shifting problem.

2/9If your A-Body shifter is giving you a problem, you can either hire this guy to drive your car, or use his advice to fix your clutch pedal.

Stock pedals on most A-Body cars have a measurement of 51/4 inches from pin to pin. Pin to pin refers to the two pins on the pedal. One pin connects the pedal to the torque-shaft arm, and the other pin is for the pedal over-center spring. In order to improve the shifting qualities of your A-Body, all you need to do is cut and extend the arm at the rear of the pedal (the arm connected to the torque-shaft connecting arm). If you increase the pin-to-pin length to six inches, the ratio of your clutch pedal is increased, thereby allowing more clutch separation when the pedal is depressed. Usually, more is better, but in this instance, extending the arm more than six inches will cause an overextension of the clutch fingers and cause binding and/or damage to the clutch assembly.

To begin, you'll need to remove your pedal over-center spring, if still installed, and the clutch pedal. To first remove the spring, have someone depress the clutch pedal while you insert washers into the spring so that they "pinch" between the spring's coils when the pedal is released. Once you have enough washers inserted, release the pedal, and the spring should come out with just a little persuasion. Once the spring is removed, you next need to remove the clutch pedal. The clutch pedal rides on a shaft that pivots inside of the brake-pedal pivot. To remove the clutch pedal, you need to remove the e-clip that holds the pedal from falling out, and the rod going from the clutch pedal to the torque shaft. The e-clip is located on the throttle-pedal side of the brake pedal pivot. Remove the e-clip, and the pedal slides out. Be sure not to lose the nylon/plastic bushings that are on the clutch's pivot shaft, and ride between the clutch pivot rod, and the brake-pedal pivot. The bushings slide off the clutch pivot arm.

3/9As you can see in the pics, the car we're working on does not have the over-center spring. This is because it has a diaphragm style clutch. To remove the pedal, unhook the torque shaft rod and then take the e-clip off. You should now be able to slide the clutch pedal out.

Now that you have the pedal out of the car, you can increase the ratio. You will need to cut the arm that the torque-shaft connecting rod connects to. Make sure that when you cut and weld the arm back in place you keep everything aligned as it was when you removed it. If you weld the arm back together and the pin for the clutch pedal rod is not straight, you will not be able to reconnect the pedal to torque shaft rod. After you cut the arm, you'll need to weld an extension piece into place. Don't skimp here and use a lesser thickness steel. This area receives a lot of pressure when the clutch is applied, so make sure it's welded back together with a good weld and the proper thickness of metal.

Once you have the pedal modified, just put it back in the car. Now, if you are not shifting your A-Body's four-speed at high rpm, this modification may not be worth your while, but for you guys that like to wind your engine tight and then shift, you'll notice a big difference in high-rpm shifting.
What this modification does is give you more pressure-plate and clutch-disc departure from the flywheel. The more plate departure that you have, the easier the transmission will shift. This modification will work whether you have a three-finger clutch or a diaphragm clutch. The only difference is that with a diaphragm clutch, your pedal may sometimes stay on the floor if you have the over-center spring in place. I wouldn't recommend using a Borg and Beck or Long style clutch without the over-center spring.